The present invention relates to an information-processing apparatus, an information-processing method and an information-processing program.
If AV (Audio Visual) data such as video and audio data is written onto and erased from a recording medium such as an optical disc repeatedly, for example, the AV data, which should be reproduced continuously from the optical disc, is recorded in recording areas separated from each other on the disc as a result of inadvertent segmentation of the recording face of the disc.
The AV data, which should be reproduced continuously from the optical disc, is also recorded in such recording areas on an optical disc due to typically an unavoidable defect existing on the disc or recorded typically as a result of a so-called non-destructive editing process.
The non-destructive editing process is an editing process adopting an editing method for merely setting so-called edit points, namely, IN and OUT points, in AV data recorded on an optical disc as an edit material but not editing (or destructing) the edit material itself. In a non-destructive editing process, there is typically created a list of edit points to be set at the edit time. The list of edit points is referred to hereafter as a play list. A result of a non-destructive editing process is then reproduced in accordance with a play list created for the edit material. That is to say, a result of a non-destructive editing process of an edit material recorded on an optical disc is reproduced by reproducing the edit material in accordance with edit points described on a play list created for the edit material. In this way, since a result of a non-destructive editing process of an edit material recorded on an optical disc is reproduced by reproducing the edit material in accordance with edit points described on a play list created for the edit material, consequently, the reproduction of the edit material is equivalent to reproduction of contiguous AV data, which should be reproduced continuously but actually recorded in recording areas separated from each other on an optical disc.
As is obvious from the above description, in the course of an operation to reproduce AV data recorded in recording areas separated from each other on an optical disc as such, in some cases, a specific portion of the AV data is reproduced from a specific recording area after reproduction of a previous portion from a previous recording area separated away from the specific recording area. In such a case, it is necessary to read out the specific portion of the AV data from the specific recording area of the optical disc after the operation to read out the previous portion from the previous recording area so that a seek operation needs to be carried out to search the recording face of the recording medium for the specific recording area separated away from the previous recording.
If it takes much time to carry out the seek operation, the specific portion of the AV data cannot be reproduced on time, resulting in an interruption of the reproduction process. That is to say, the AV data cannot be reproduced in a real-time manner.
In order to solve the problem described above, the AV data is reproduced from the optical disc by typically first storing the AV data read out from the disc in a buffer and then processing the AV data stored in the buffer.
In such a solution, a rate at which the AV data is read out from the optical disc is generally set at a value higher than a reproduction rate for the AV data. By reading out the AV data from the optical disc at such a relatively high rate, the AV data is supplied to the buffer at a rate higher than a rate at which the AV data is output from the buffer. Thus, basically, the AV data read out from the optical disc is gradually accumulated in the buffer. If a seek operation takes place, however, no AV data is read out from the optical disc during the seek operation. Accordingly, the AV data is merely output from the buffer for the reproduction purpose so that the amount of the AV data accumulated in the buffer decreases. If the seek operation is not completed so as to allow AV data to be read out from the optical disc again before all AV data accumulated in the buffer is read out from the buffer, an underflow occurs in the buffer, interrupting the reproduction process.
If the amount of AV data accumulated in the buffer prior to a seek operation is sufficiently large, nevertheless, the seek operation does not cause the reproduction process to be interrupted. If AV data is read out from the optical disc continuously, the amount of AV data accumulated in the buffer increases. If a seek operation is carried out and no AV data is read out from the optical disc, on the other hand, the amount of the AV data accumulated in the buffer decreases. Thus, in order to make the amount of the AV data accumulated in the buffer prior to a seek operation sufficiently large, it is necessary to continuously read out enough AV data from the AV disc before a seek operation occurs. In turn, in order to make it possible to continuously read out enough AV data from the AV disc, it is necessary to continuously record the AV data on the optical disc in contiguous recording areas each having a large size to a certain degree.
Thus, in accordance with a technology disclosed in documents such as Japanese Patent Laid-open No. Hei 11-98447, video data and audio data are recorded in contiguous recording areas of an optical disc wherein the recording areas are obtained by splitting the recording face of the optical disc into concentric circles so that the video data and audio data can be recorded continuously in the recording areas each contiguous to a certain degree.
Nevertheless, even if AV data is recorded continuously on the optical disc in recording areas each contiguous to a certain degree, in dependence on the disc apparatus, a seek operation may still make it impossible to reproduce the AV data in a real-time manner.
That is to say, the buffer used for temporary storing AV data read out from an optical disc has a size varying in dependence on the disc apparatus. In the case of a disc apparatus with a buffer having a large size, the AV data can be reproduced in a real-time manner. In the case of a disc apparatus with a buffer having a small size, on the other hand, the AV data cannot be reproduced in a real-time manner sometimes.
In addition, AV data may need to be reproduced at a high speed instead of a normal speed. Even though the AV data can be reproduced in a real-time manner at the normal speed, the AV data cannot always be reproduced in a real-time manner at the high speed. Here the reproduction in a real-time manner means reproducing the AV data at a requested reproduction rate without interruption.
In addition, interruption of a reproduction process in a disc apparatus after a start of the reproduction process carried out at a reproduction rate requested by the user makes the user feel a sense of incompatibility.
In order to solve the problems described above, it is necessary to determine whether or not the AV data can be reproduced at a reproduction rate requested by the user in a real-time manner and inform the user of an outcome of the determination before reproduction of the AV data is started.
In order to determine whether or not the AV data can be reproduced in a real-time manner, it is necessary to actually read out the AV data from the optical disc and check whether or not the operation to read out the AV data from the disc is in time for the reproduction of the AV data at the reproduction rate requested by the user.
However, the operations carried out to actually read out the AV data from the optical disc and to determine whether or not the AV data can be reproduced in a real-time manner every time the user issues a reproduction command consume much time and are also cumbersome.